The Government of Ireland Act, 1920 (also known as the Fourth Home Rule Act or in terms of strict accuracy the Better Government of Ireland Act) was passed by the Parliament of the United Kingdom to provide for Irish home rule. (Three earlier Bills had been introduced, in 1886, 1893 and 1914. Only the latter was passed, but it never came into force, due to the First World War and then the Easter Rising in 1916.)

The Act, introduced by the Government of David Lloyd George, provided for two partitioned Irish home rule states, Northern Ireland and Southern Ireland. Their creation was a compromise produced by the British Government when faced with the demand by Irish nationalists for home rule and the demand of Irish unionists that home rule not be conceded. Each state was to have a two-chamber parliament, a House of Commons and a Senate. Elections in both states for both lower houses took place in May 1921.

The Northern Ireland state came into being in 1921. At its opening, held in Belfast City Hall, King George V made a famous appeal for Anglo-Irish and north-south reconciliation. The speech, drafted by the government of David Lloyd George on recommendations from Jan Smuts, Prime MInister of the Union of South Africa, with the enthusiastic backing of the King, opened the door for formal contact between the British Government and the Republican administration of Eamon de Valera.

With only 4 MPs and 15 appointed senators turning up for the state opening of parliament in the Royal College of Science in Dublin (now Government Buildings) in June 1921, the parliament was suspended.